WoW64 (Windows 32-bit on Windows 64-bit) is a subsystem of the Windows operating system capable of running 32-bit applications and is included on all 64-bit versions of Windows—including Windows XP Professional x64 Edition, IA-64 and x64 versions of Windows Server 2003, as well as 64-bit versions of Windows Vista, Windows Server 2008, Windows 7 and Windows 8. In Windows Server 2008 R2 Server Core, it is an optional component. WoW64 is designed to take care of many of the differences between 32-bit Windows and 64-bit Windows, particularly involving structural changes to Windows itself.